The communications industry is rapidly changing to adjust to emerging technologies and ever increasing customer demand. This customer demand for new applications and increased performance of existing applications is driving communications network and system providers to employ networks and systems having greater speed and capacity (e.g., greater bandwidth). In trying to achieve these goals, a common approach taken by many communications providers is to use packet switching technology. Increasingly, public and private communications networks are being built and expanded using various packet technologies, such as Internet Protocol (IP).
As IP networks become mission critical infrastructure, network High Availability (HA) grows in importance. Meanwhile, SONET/SDH resilience with sub-50 ms protection switch times has become industry standard, setting the benchmark for other network resilience techniques. While the importance of this exact value of protection switch time can be argued in IP networks due to the re-transmission and resilience properties of TCP and other higher-level protocols, it is clearly beneficial to limit the traffic loss. The benefits are most obvious for real-time applications like Voice over IP where multi-second losses caused by network convergence directly affect end users.
Internet traffic continues to grow faster than Moore's law allows the underlying technology to increase in speed. As a result, the number of links connecting routers is increasing. The trend is toward larger routers with more interconnects. Quite often multiple links connect two adjacent routers, resulting in the emergence of link aggregation techniques. Aggregated links can be configured as a single interface from IP routing perspective, making a single Layer 2 (L2) link failure appear to Layer 3 (L3) as only a reduction in bandwidth. At the same time legacy SONET/SDH networks continue to be used and deployed. As a result routers are being interconnected across SONET/SDH networks using Automatic Protection Switching (APS). SONET-derived ring resiliency principles are also being applied to rings of routers in Resilient Packet Rings (RPR) solutions. Another important networking trend is the wide deployment of Multiprotocol Label Switching (MPLS), which adds a number of new capabilities to IP Networks, with associated protection switching capabilities of connection-oriented MPLS Traffic Engineering (TE) and MPLS Fast Re-Route (FRR). With a variety of different networking layers at which protection switching could be performed in response to a detected condition and the unlimited number of possible network and equipment configurations, desired is a mechanism to provide protection switching which may include coordinating among multiple protection switching mechanisms the actual protection switching performed in response to a particular failure.